2 * Copyright 2005-2010 the original author or authors.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 * This package provides test library for database testing in general and JPA testing
19 * specifically. As part of this it provides a means to transparently start an inmemory
20 * database from a junit test or connect to an external database. Also, given a persistence
21 * unit it is easy to start testing it in a junit test with only a few lines of code.
25 * The main use cases are explained below:
28 * <li> <a href="#db-basic">Basic database testing, transparently connecting to a database</a>
30 * <li> <a href="#db-basic-external">Connecting to an external database</a>
32 * <li> <a href="#db-utils">Executing code within a JDBC transaction</a>
34 * <li> <a href="#db-unit">Using DB Unit in your tests</a>
36 * <li> <a href="#db-jpa-basic">Basic JPA testing</a>
38 * <li> <a href="#db-jpa-plus-jdbc">JPA testing combined with JDBC and DBUnit</a>
40 * <li> <a href="#db-jpa-services">Testing a service that requires a transaction</a>
45 * See the <a href="#design-overview">design overview</a> for a an overview of the design.
49 * <h2>Basic database testing, transparently connecting to a database</h2>
51 * Starting the database:
53 * Database db = DatabaseBuilder.getDatabase();
54 * DataSource dataSource = db.start();
56 * If nothing is specified in the user's environment, an inmemory database is started (derby).
57 * Using the datasource is just standard JDBC now.
58 * Stopping the database
63 * <a name="db-basic-external">
64 * <h2>Connecting to an external database</h2>
67 * Connecting to an external database can be done by requiring the 'external' capability on
68 * the database provider.
70 * Database db = DatabaseBuilder.getDatabase(DatabaseProvider.CAPABILITY_EXTERNAL);
72 * This also requires a number of environment variables or system properties to be set,
73 * see {@link ExternalDatabase}.
76 * However, the most convenient way to set the capabilities is usually to set a system property or environment
77 * variable see the javadocs of {@link DatabaseBuilder}. and
78 * specifically {@link DatabaseBuilder#DB_CAPABILITIES_PROP}
83 * <h2>Executing code within a JDBC transaction</h2>
86 * To execute code withing a JDBC transaction, use the {@link DatabaseUtils} and
87 * use the {@link DatabaseUtils#executeInTransaction(org.wamblee.support.persistence.DatabaseUtils.JdbcUnitOfWork)}
91 * DatabaseUtils dbutils = new DatabaseUtils(dataSource);
92 * boolean result = dbutils.executeInTransaction(
93 * new JdbcUnitOfWork<Boolean>() {
95 * public Boolean execute(Connection aConnection) throws Exception {
96 * ResultSet res = jpaTester.getDbUtils().executeQuery(
97 * aConnection, GROUP_QUERY, aGroup);
102 * {@link DatabaseUtils} also provides various other utility methods to work with JDBC queries.
105 * <h2>Using DB Unit in your tests</h2>
108 * <p>To work with <a href="http://dbunit.org">DBUnit</a>, {@link DatabaseUtils#createDbTester(org.dbunit.dataset.filter.ITableFilterSimple)}
109 * must be used passing it in the tables to use in the form of a {@link org.dbunit.dataset.filter.ITableFilterSimple}
113 * IDatabaseTester dbtester = dbutils.createDbTester(new ITableFilterSimple() {
114 * public boolean accept(String aTableName) throws DataSetException {
115 * return aTableName.startsWith("XYZ_");
120 * <p>The reason for using a <code>DatabaseUtils</code> instead of DBUnit directly is that
121 * <code>DatabseUtils</code> will keep track of connections and close them when <code>DatabaseUtils</code>
124 * <a name="db-jpa-basic">
125 * <h2>Basic JPA testing</h2>
128 * First step is to create a {@link PersistenceUnitDescription} that matches the persistence unit you
131 * <p>Second step is to make sure that all entities are listed explicitly in your
132 * <pre>persistence.xml</pre>. Currently, class path scanning appears to fail when
134 * Specifying all entities explicitly is not necessarily a bad thing as it is also more efficient.
138 * Now create a <code>JpaTester</code> in your test code:
142 * public void setUp() throws Exception {
144 * // First we create the JpaTester by telling us which persistence unit we
145 * // are going to test
146 * jpaTester = new JpaTester(new MyPersistenceUnit());
152 * Then in test code execute some JPA code within a unit of work:
155 * jpaTester.getJpaBuilder().execute(new JpaUnitOfWork<Void>() {
156 * public Void execute(EntityManager aEm) {
157 * MyEntity entity = new MyEntity("a", "b");
158 * aEm.persist(entity);
164 * <a name="db-jpa-plus-jdbc">
165 * <h2>JPA testing combined with JDBC and DBUnit</h2>
167 * <p>The <code>JPATester</code> provides access to all required object. It is usually convenient to
168 * get them directly from the <code>JPATester</code> after initializing it:
170 * builder = jpaTester.getJpaBuilder();
171 * dbtester = jpaTester.getDbUtils().createDbTester(new MyTables());
172 * dbutils = jpaTester.getDbUtils();
175 * <a name="db-jpa-services">
176 * <h2>Testing a service that requires a transaction</h2>
179 * <p>Using {@link TransactionProxyFactory} it is possible to create a proxy for a given
180 * service interface to provide the semantics of 'requires new' transaction semantics.
182 * TransactionProxyFactory<Service> factory = new TransactionProxyFactory<Service>(
183 * jpaTester.getJpaBuilder(), Service.class);
184 * Service service = new ServiceImpl(factory.getTransactionScopedEntityManager());
185 * Service proxy = factory.getProxy(service);
186 * proxy.execute(...);
190 * In the above example, the <code>Service</code> POJO requires an {@link EntityManager} in its
191 * constructor and it is passed a transaction scoped entitymanager from the factory. This entitymanager
192 * is in fact a so-called contextual reference.
193 * Next, the proxy is obtained from the factory. Invoking any method on it will make sure a new
194 * transaction is started and a new entity manager is created for the scope of that transaction.
197 * <a name="design-overview">
198 * <h2>Design overview</h2>
201 * <h3>Database transparency</h3>
204 * <img src="doc-files/Class_Diagram__org.wamblee.support.persistence__database.jpg"
208 * {@link DatabaseProvider} uses <code>java.util.ServiceLoader</code> to find all implementations
209 * of {@link DatabaseProvider} on the classpath. It then asks the database providers whether
210 * they support the required capabilities (by default inmemory), and the first provider that
211 * supports the capabilities is used to create the database.
214 * Note that the <code>Database</code> interface is not intended to always create a database.
215 * It will do so for {@link DerbyDatabase} (inmemory), but with {@link ExternalDatabase}
216 * it simply connects to an external database based on system properties or environment
220 * <h3>JPA tester overview</h3>
223 * <img src="doc-files/Class_Diagram__org.wamblee.support.persistence__jpatester.jpg"
227 * <p><code>JPATester</code> is responsible for:</p>
229 * <li> Starting or connecting to a database, using {@link DatabaseBuilder}.
231 * <li> Registering the acquired datasource in JNDI by first stubbing JNDI
232 * using {@link org.wamblee.support.jndi.StubInitialContextFactory}.
234 * <li> Creating the {@link JPABuilder} that will do the JPA heavy lifting.
236 * <li> Creating the {@link DatabaseUtils} for JDBC and DBUnit testing.
242 package org.wamblee.support.persistence;